The 3-year-old dog known as "Cooper" was euthanized last Monday after his partner, officer Troy Newell, noticed the animal had been lethargic. The dog had been examined by a local veterinarian and a Tulsa animal clinic and diagnosed with advanced kidney failure.

Police Chief Tom Holland says the preliminary oral report that Oklahoma State University veterinarians gave the dog's handler noted that Cooper might have been poisoned. Holland says the report didn't contain many details but that there was an "unacceptable amount of antifreeze" in Cooper's system.

Holland says the department is investigating but there are no suspects.